UPSC Prelims 2005 Q88: Science & Technology – Energy & Environment
Assertion (A): The main constituent of the Liquefied Petroleum Gas is methane.
Reason (R): Methane can be used directly for burning in homes and factories where it can be
supplied through pipelines.
- (a) Both A and R are individually true and R is the correct explanation of A
- (b) Both A and R are individually true but R is not the correct explanation of A
- (c) A is true but R is false
- (d) A is false but R is true
Answer: (d) A is false but R is true
Explanation
LPG, methane and natural gas
| Part | Verdict |
|---|---|
| A. Main constituent of LPG is methane | False: LPG is mainly propane and butane |
| R. Methane can be used directly in homes and factories through pipelines | True — piped natural gas and CNG |
A is false: LPG consists of propane and butane. R is true: methane, the main part of natural gas, can be piped for domestic and industrial use.
Answer: (d) A is false but R is true.
Why each option is right or wrong
- (a) Incorrect. A is false, as LPG is not mainly methane.
- (b) Incorrect. A is false, as LPG is not mainly methane.
- (c) Incorrect. R is true, as methane is piped as natural gas.
- (d) CORRECT. A is false because LPG is propane and butane, while R is true.
Key point
LPG: propane + butane. CNG and PNG: mostly methane.
Remember
LPG is mainly propane and butane, not methane.
Common mistakes
- Confusing LPG with CNG or piped natural gas.
- Assuming the cylinder gas is methane.
- Missing that A is false and R is true.
Exam tip
Methane is lighter than air; LPG is heavier, and so is stored in cylinders.
Sources
- NCERT Class XI Chemistry — Hydrocarbons
- Bureau of Indian Standards — IS 4576: Liquefied Petroleum Gases — Specification